Custom Icons, script path register
Thanks for response.

Ok, now everything works..

Is there cleaner way for doing this or I need always register new icon ?

import os
import bpy

bl_info = {
    "name": "IPG Selection",
    "author": "InvisibleParrot",
    "version": (0, 0, 1),
    "blender": (2, 77, 0),
    "location": "View3D &gt; Edit Mode",
    "description": "IPG tools of trade",
    "warning": "",
    "wiki_url": "",
    "category": "IPG Tools"}


preview_collections = {}


class PreviewsExamplePanel(bpy.types.Panel):
    """Creates a Panel in the Object properties window"""
    bl_label = 'Selection'
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'TOOLS'
    bl_category = 'IPG Tools'


    def draw(self, context):
        layout = self.layout

        col = layout.column(align = True)
        this_icon = preview_collections["custom_icons"]["custom_icon"].icon_id
        col.operator("render.render", text="Unwrap", icon_value=this_icon)
        this_icon = preview_collections["custom_icons"]["custom_icon2"].icon_id
        col.operator("render.render", text="Unwrap2", icon_value=this_icon)
        this_icon = preview_collections["custom_icons"]["custom_icon3"].icon_id
        col.operator("render.render", text="Unwrap3", icon_value=this_icon)
        this_icon = preview_collections["custom_icons"]["custom_icon4"].icon_id
        col.operator("render.render", text="Unwrap4", icon_value=this_icon)



def register():

    # Note that preview collections returned by bpy.utils.previews
    # are regular py objects - you can use them to store custom data.
    import bpy.utils.previews
    pcoll = bpy.utils.previews.new()

    # path to the folder where the icon is
    # the path is calculated relative to this py file inside the addon folder
    my_icons_dir = os.path.join(os.path.dirname(__file__), "icons")

    # load a preview thumbnail of a file and store in the previews collection
    pcoll.load("custom_icon", os.path.join(my_icons_dir, "C_Black.png"), 'IMAGE')
    pcoll.load("custom_icon2", os.path.join(my_icons_dir, "C_Blue.png"), 'IMAGE')
    pcoll.load("custom_icon3", os.path.join(my_icons_dir, "C_Yellow.png"), 'IMAGE')
    pcoll.load("custom_icon4", os.path.join(my_icons_dir, "C_Red.png"), 'IMAGE')

    preview_collections["custom_icons"] = pcoll

    bpy.utils.register_class(PreviewsExamplePanel)

    bpy.utils.register_module(__name__)



def unregister():

    for pcoll in preview_collections.values():
        bpy.utils.previews.remove(pcoll)
    preview_collections.clear()

    bpy.utils.unregister_class(PreviewsExamplePanel)

    bpy.utils.unregister_module(__name__)


if __name__ == "__main__":
    register()